He added: "I am absolutely convinced this was an accident so I'm mystified, after 13 years, how any new information can possibly allege anything other than [that] this was a tragic accident."

Scotland Yard said it is "scoping" the information and "assessing its relevance and credibility".

The claims were passed to the Metropolitan Police by the Royal Military Police (RMP), which was told of them by the former parents-in-law of a former soldier based on information that the ex-soldier had talked about in the past, according to a military source.

A letter given to the RMP is said to allege that the SAS was "behind Princess Diana's death", according to the Sunday People, and to also refer to the princess's "secret diary", in which she allegedly made certain allegations.

The People said that the letter claimed the soldier was the special forces member who was the former housemate of Sergeant Danny Nightingale, who was found guilty of illegally possessing a gun and ammunition.

A statement issued by Scotland Yard said: "The Metropolitan Police Service is scoping information that has recently been received in relation to the deaths and assessing its relevance and credibility.

"The assessment will be carried out by officers from the specialist crime and operations command. This is not a re-investigation and does not come under Operation Paget."